Question 1
A high-temperature electric arc of _____ is used for the manufacture of silicon carbide.
A. 1500oF
B. 3000oF
C. 4500oF
D. 7500oF
View Answer
Answer: Option C
Explanation:
Silicon carbide is an artificially manufactured abrasive material. This is done by mixing sand, coke, and sawdust and passing it through an electric arc at 4500oF. This mixture is converted into silicon carbide and crushed.
Question 2
Conversion of a tetrahedral unit into a three-dimensional structure gives a ______ structure.
A. Vitreous
B. Sheet
C. Chain
D. Framework
View Answer
Answer: Option D
Explanation:
When a silicate tetrahedral unit extends into three dimensions, it gives a framework structure. On the other hand, a sheet structure extends into a two-dimensional plane similar to how framework extends in three-dimensions.
Question 3
Quartz and Feldspar are examples having ______ structure
A. Tetrahedron
B. Sheet
C. Poly tetrahedral
D. Framework
View Answer
Answer: Option D
Explanation:
When a silicate tetrahedral unit extends into three dimensions, it gives a framework structure. It has a relatively low density, low atomic packing factors, and good hardness. Common examples of framework structures can be found in cristobalite, quartz, and Feldspar.
Question 4
Sandpaper is a common application of ______ abrasives.
A. Garnet and flint
B. Rottenstone and pumica
C. Walnut shells
D. Silicon carbide
View Answer
Answer: Option A
Explanation:
Garnet and flint are natural abrasives typically used for sandpaper. Walnut shells find their application for cleaning of aircraft engine parts, whereas rottenstone and pumica are used for wood finishing.
Question 5
The ability of a material to exist in more than one crystal structure is known as _______
A. Polymorphism
B. Allotropy
C. Polyhedral phase
D. Lattice
View Answer
Answer: Option A
Explanation:
Polymorphism is the property of a material which allows it to exist in more than one form of space lattice or crystal structure. When such a process is reversible, it is defined as allotropy.
Question 6
The polishing of cast iron and finishing of stainless steels are applications of ______
A. Silicon carbide
B. Boron carbide
C. Tungsten carbide
D. Aluminum oxide
View Answer
Answer: Option D
Explanation:
Aluminum oxide is an abrasive which is obtained by heating of aluminum salts or from ores of bauxite. It has a lighter color compared to silicon carbide and is not as hard, but is more resistant to impact. It is used for polishing cast irons, non-ferrous materials, and for giving a lustrous finish to stainless steels.
Question 7
What is a common application of diamond?
A. Drilling of rocks
B. Sandpaper
C. Wood finishing
D. Polishing of metals
View Answer
Answer: Option A
Explanation:
Diamond is a natural abrasive and is known as the hardest material. It is used for wire drawing dies, drilling rocks, and dressing grinding wheels. It is also used for polishing of hard carbide metals, glass, and ceramics. Emery, on the other hand, is used for general purpose metal polishing.
Question 8
What is the composition of a double tetrahedral structure?
A. SiO4
B. Si2O7
C. Si3O9
D. Si5O9
View Answer
Answer: Option B
Explanation:
A double tetrahedral silicate structure is produced as a result of overcoming the deficiency of electrons in oxygen. Its composition is Si2O7 whereas that of a polyhedral unit is Si3O9.
Question 9
Which abrasive has a common trade name as carborundum?
A. Aluminum oxide
B. Silicon carbide
C. Tungsten carbide
D. Boron carbide
View Answer
Answer: Option B
Explanation:
Silicon carbide (SiC) is an artificial abrasive used for making grinding wheels, pipes, and pumps. It is better known by its trade name of carborundum. Aluminum oxide is another artificial abrasive.
Question 10
Which of the following is not a natural abrasive?
A. Emery
B. Quartz
C. Silicon carbide
D. Sandstone
View Answer
Answer: Option C
Explanation:
An abrasive is a common ceramic material which is hard and mechanically resistant. Synthetic abrasives are preferred as they can be made as per the desired properties and also exhibit more uniformity. Diamond, sandstone, quartz, and emery are a few examples of natural abrasives. Silicon carbide and aluminum oxide are examples of synthetic abrasives.
Question 11
Which of the following is regarded as a modern abrasive?
A. Tripoli
B. Silicon carbide
C. Pumica
D. Boron carbide
View Answer
Answer: Option D
Explanation:
Boron carbide and tungsten carbide are generally regarded as modern abrasives. They are close to the hardness of a diamond, which is a natural abrasive. Boron carbide is used for polishing pastes.